Question Number 78627 by mathmax by abdo last updated on 19/Jan/20
$${explicite}\:{f}\left({x}\right)=\int_{−\infty} ^{+\infty} \:\frac{{arctan}\left({xt}\:+\mathrm{1}\right)}{{t}^{\mathrm{2}} \:+{x}^{\mathrm{2}} }{dt}\:\:{with}\:{x}>\mathrm{0} \\ $$